NOTES ON SCIENCE, MECHANICAL INVENTIONS, ETC.

New Zealand Herald, Volume XXVI, Issue 9452, 24 August 1889, Page 4 (Supplement)

NOTES ON SCIENCE, MECHANICAL INVENTIONS, ETC.

DEGENERATION OF THE HUMAN TEETH.

The law of retardation exhibits itself ill the teeth of the higher races of mankind in a highly inconvenient manner. The greatly developed brain requires all the available room in the skull; there is no spaco left for the attachment of muscles of a powerful jaw. There is consequently no room left for either the wisdom teeth or the upper incisors; the wisdom teeth are retarded, often cause great pain, and decay early. The sccond incisors appear in startling and unexpected places, and often (in America especially) do not cut the gum at all. Prof. Cope says that American dentists have observed that the third molar toeth (wisdom teeth) are in natives of the United States very liable to imperfect growth or suppression, and to a degree entirely unknown among savage or even more civilised races. The same suppression has been observed in the outer pair of superior incisors. This is owing not only to a reduction in tho size of the arches of the jaw, but to successively prolonged delay in the appearance of the teeth. In the same way men and the manlike apes have fewer teeth than tho lower monkeys, and these again fewer than tho insectivorous mammals to which they are most nearly allied. When this difference in dentition has been established, civilised man may claim to place himself in a new species, apart from low savages as well as from high apes.Popular Science Monthly. PHYSICAL EFFECTS OF ALCOHOL. But if the physical results of alcohol arc varied, much more diverse are its effects upon the mental and moral nature of man. Indeed, they are as multiform as man himself. One general classification only is possible. Certain individuals (fortunately tho small minority) are always pleasureably affected by stimulants. Each successive dose arouses in them increased exhilaration, and when intoxication supervenes, their sensations arc delightful. Their every senso is exalted ; they fancy themselves endowed with every giftwith all power and possession. As is often remarked, these aro generally men of tho most brilliant intellect and of the most charming moral qualities. Once led captive by alcohol, theso unfortunates seldom have sufficient power of will to refrain from renewed indulgence. No moral considerations avail to restrain thorn, and, with few exceptions, they yield wholly, finally, and fatally to tho tempter. For such men total abstinence is the only refuge. . Upon the largo of men the effects of alcohol taken to intoxication arc clearly and essentially different; although at lirst exhilarated, repeated indulgence brings drowsiness, dulness of apprehension, anaesthesia vertigo, nausea, and vomiting— in short, bodily and mental symptoms which are excessively disagreeable. Of this class very few become drunkards, and those are men to whom anaesthesia bccomcs desirable as a temporary refuge from bodily pain and mental distress. Herein lies the sole explanation of the fact that the proportion of drunkards to moderate and habitual drinkers remain so small.—Dr. W. S. Searlc, in North American Review. AX ADJUSTABLE COUNTERSHAFT. Every machinist knows that it is best to keep driving belts just as loose as the nature of the work will admit, for by so doing the friction and wear upon the journals is much reduced, the life of the belt is very great ly increased, and it is much more easily handled and shifted from step to step of the cone pulleys when changing speed. Where only one thing is done upon a machine, it is, of course, possible to keep the belt about as loose as tlio work it has to do will permit ; but in the case of a lathe, milling machine, or, in fact, most machine tools upon which a variety of work is done, there are times when it Is necessary to have the belt as tight as possible, and yet, perhaps, most of the time it could be quite loose. Air. Frank li. Hynes, of Rochester, N.Y., has devised and patented an improved countershaft to enable a belt to be instantly adjusted to the degree of tension desirable for the work in hand. It is claimed that in the use of such a countershaft no greater tension need be upon the belt, at any time than is absolutely necessary to make it pull the cut, and thereby, as every machinist will know, a great deal of destructive wear and tear upon bells, machine, and countershaft journals may be avoided, besides effecting a saving of power, time (otherwise spent in lacing and unlacing belts), and of.patience. FELLING TREES BY ELECTRICITY. Hitherto machines for felling trees have been driven by steam-power, but this is sometimes inconvenient, especially in thick woods, and electric power has recently been adopted in the Oalician forests. Usually in ■ such machines the trunk is sawn, but in this case it is drilled. When tho wood is of a soft nature, the drill has a sweeping motion, and cut* into the trunk by means of cutting edges 011 its aides. The drill is actuated by un electric motor mounted on a carriage, which is 'brought up closc to the tree and shackled to it. The motor is capable of turning around its vertical axis, and the drill is geared to it in such a manner that it can turn through an arc of a circle and make a swooping cut into the trunk. The first cut made, tho drill is advanced a few inches, and another section of wood removed in the same way until the trunk is half severed. It is then clamped to keep the cut from closing, and the operation continued until it would be unsafe to go on. The remainder is finished by a hand-saw or an ax. The current is conveyed to the motor by insulated loads brought through the forest from a generator placed in some convenient .site. DANGEROUS PRACTICES. The fifth annual report of the State Inspector of Workshops and Factories in Ohio is full of instructive matter. Among other things he makes some good suggestions regarding the care of boilers and fittings, which wo quote and commend :—" Another dangerous practice is tho caulking of joints in steam pipes while pressure is on. If pipes or coverings are corroded, as they very frequently are, there is danger that the chisel or caulking tool may bo driven through the pipe. In such a case the workman is likely to be seriously scalded. Tho practice of screwing up man-hole, hand-hole, and similar plates, whilo boilers are under pressure, to stop leakage, is of a similar nature and should be as strongly discountenanced. A groat many accidents have been caused in this manner. Tho following occurred some years ago : A battery of three horizontal tubular boilers was fired up, and on raising steam the joint of one of the man-hole plates was found to leak quite badly. Instead of letting down the steam and repacking the joint, a wrench was applied and tho attempt was made to stop the leak by screwing up 011 the bolt. This proving insufficient, a long piece of pipo was slipped over the handle of the wrench and more force applied. Tho immediate result was tho fracture of the man-hole frame, tho explosion of the boiler, tho destruction of about £2000 worth of property, and tho loss of three lives. MISCELLANEOUS. Adulteration of flour with potato flour may be detected by means of acids. Take a spoonful and pour upon it a littlo nitric acid; if the flour be of wheat, it will be chauged to an orange yellow ; if wholly of potato Hour, the colour would not be altered but the flour formed into a tenacious jelly ; if, therefore, the flour bo adulterated with potato flour, it will not be difficult to decide. Again, take a spoonful of the flour and pour upon it a littlo muriatic acid ; if the flour bo of pure wheat, it will bo changed to a deep violet colour, without odour ; but if potato flour be mixed in it, it will then have an odour like that of rushes. M. Leon Esquillo, a Mexican, it is stated, has perfected a marvellous invention in electricity and photography. By speaking in a photophone transmitter, which consists of a highly polished diaphragm, reflecting a ray of light, this ray of light is set into viabrations, and a photograph is made of it 011 a travelling band of sensitized paper. !Now cotnes the wonderful part. If the image of this photographic tracing is projected by means of an electric arc or oxyhydrogen light upon a soleniuui receiver, the original speech is then heard. It is ovident that there is no limit to the development of this peculiar combination of methods. An important experiment has been tried successfully at Ottawa, Out. A mill has been established which makes paper pulp out "f sawdust. It is now using the product of one mill. The paper made wholly from sawdust is said to form an admirable sheathing that is fit for building after being tarred and dried. A bettor quality of paper is made by using one-fourth waste paper. The plant cost £3000, and consists of American machinery, with the exception of tho grinders. The mill has a capacity for converting about 12,000 tons of sawdust into pulp aunually.